Prior Art
The closest prior art of which applicant is aware is as follows:
U.S. Pat. No. 3,607,083; Thiers; Sept. 21, 1971 PA1 U.S. Pat. No. 4,233,029; Nov. 11, 1980 PA1 U.S. Pat. No. 4,254,083; Columbus; Mar. 3, 1981 PA1 U.S. Pat. No. 4,264,560; Natelson; Apr. 28, 1981 PA1 U.S. Pat. No. 4,271,119; Columbus; June 2, 1981 PA1 U.S. Pat. No. 4,310,399; Columbus; Jan. 12, 1982 PA1 U.S. Pat. No. 4,399,102; Karlberg; Aug. 16, 1983 PA1 U.S. Pat. No. 4,426,451; Columbus; Jan. 17, 1984
Although the above patents involve fluid flow systems which may utilize capillary flow principles, the basic concept of shifting a control fluid/principal fluid interface for the purpose of influencing or controlling principal fluid flow is not present therein.